Manufacture of covered tubing



Nov. 11, 1941.

K. PAPE MANUFACTURE OF covrmrm TUBING FiledApril 1940 2 Sheets-Sheet l INVENTOR. 50 W By W% :04

ATTORNEY5 Nov. 11, 1941. K, PAPE 2,262,514

MANUFACTURE OF COVERED TUBING Filed April 27, 1940 2 Sheets-Sheet 2 INVENTOR.

ATTORNEYS Patented Nov. 11,

Karl Pape, Dover, N. 3., assignor to Reslstoflex Corporation, Bellejville, N. J., a corporation of New York I Application April 27, 1940, Serial No. 331,952

7 Claims.

This invention relates to the manufacture of flexible tubing which has a covering of textile fabric formed directly thereon.

More j particularly, the invention pertains to the manufactureof fabric covered tubing which has as its core or inner layer an extruded tube of flexible synthetic plastic material, such, for example, as the tubing of plastlcized polyvinyl alcohol which is described in U. S. Patent No.

2,053,112 issued to Ernst Schnabel. It isapplicable generally, however, to other materials having similar physical characteristics.

.In the manufacture of extruded tubing from plastic materials, certain minor irregularities and variations in its diameter are unavoidable by 1 reason of the nature. of the extrusion process.

The material is forced through a die under pres.- sure in a very plastic state, frequently with the application of internal air pressure to keep the walls of the tubing from collapsing while soft,

and slight variations in such pressure, in the rate of extrusion, or in other factorsmay cause slight increases and decreases in the size of the tubing.

In accordance with present methods of covering such tubing inthe ordinary braiding machine or in a loom for weaving tubular fabric, the irregularities in the form or the diameter of the tubing remain in the finished product because the fabric covering follows the contour of the tubing as it is formed thereon. Suchirregularities give rise to a number of difliculties in subsequent manufacturing processes to which the, covered tubing is subjected, among which the following may be mentioned: Subsequent coatings or coverings such as lacquer, rubber or the like are applied over the'fabric cover, in the application of I which the tubing is drawn through a die of fixed size. If the diameter of the covered tubing is not uniform within small tolerances, such sub sequent coating is not uniform in thickness. It

may be extremely thin at those spots where the tubing is oversize and be so thick as to smear or be otherwise marred where the tubing is undersize. In use, the tubing is usually'provided with fittings or couplings which are manufactured in standard sizes. Ifthetubing size varies, it becomes impossible to assure a proper fit with these '1 members or a uniform strength of the assembled unit at the points of attachment.

It is an object of this invention to eliminate these diificulties and to produce a covered tubing of greatly improved uniformity, in which any irregularities existing in the dimensions or surface of the uncovered stock have been removed.

. Other objects are the'production of a uniform bonding of the fabric cover to the tubing and the provision of means for uniformly subjecting the covered tubing to solvent vapors for this purpose, said means being rendered ,inoperative automatically upon stopping of the machine by which the covering is formed and applied.

Afurther object is the formation of a braided or otherwise woven covering of great regularity and smoothness directly on tubing which is flexible and elastic.

"To these ends the invention comprises nov 1 processes and. apparatus as hereinafter described.

In accordance with this invention the coverin is woven on the tubing within the orifice of a die, which is fixed at the appropriate point in any suitable fabric forming machine, the said orifice being of such relative size and shape as to give to the tubing which is drawn through it a uniform size at the time thecover is formed thereon. The covering is applied to the tubing under a uniform tension which is sufflcient substantially to' maintain the uniformity of size imparted to the tubing by the die. tion of the die upon the tubingv and to prevent the formation of folds or creases in the tubing as it is drawn through the die, and for other reasons hereinafter explained, the tubing is preferably maintained under an inflating pressure during the carrying out of the covering process. This may readily be done by closing one end of the tubing and connecting the other end to a source of compressed air. The invention may be covering of tubing 7 vinyl alcohol, the essential characteristics of practiced, however, without such inflation.

It is to be understood that the term weaving as used hereinafter or in the claims is intended to include braiding as a particular type of weaving, and that reference to fabric or "textile fabric" includes not only coverings formed of the various types of fibrous yarns but also coverings formed of wires or other filaments. i

As an illustration of how the invention may be practiced, the carrying out of the process and the apparatus. used "therefor will now be described.

To assure the proper ac- This embodiment of the invention involves the of extruded plasticized polywhich maywelllbe kept in mind fora better understanding of the description. This material is flexible, very tough and somewhat elastic. 'Tubing made thereof is thus capable of being slightly expanded when filled with compressed air.

Polyvinyl alcohol ism or less soluble in water and capable of being softened slightly and rendered adhesive'on its surface when subjected almost all other solvents.

.for supplying compressed air to the tubing;

the braiding die alone;

. mon type of b to steam for only a short time. It is insoluble in The covering of the tubing may be accomplished in a braiding machine of "well-known construction, modified by the addition of the die 5 referred to above, a pair of auxiliary gripping wheels preferably being used for drawing the tubing through the die at a uniform rate, and a steaming chamber through which the tubing passes as it leaves the machine. The apparatus 1 employed is illustrated in the {drawings in which:

Fig. 1 shows certain essential parts of a common type of braiding machine with the-additions referred to above, the steaming device and means 15 Fig. 2 is a cross-section through the braiding die and its holder, showing the tubing as it passes therethrough;

Fig. 3 is a longitudinal cross-section through Fig. 4 shows the auxiliary gripping wheels which draw the tubing through the die together with associated parts of the braiding machine;

Fig. 5 illustrates the means for controlling the steaming of, the tubing in association with apart 25 of the braiding machine;

Fig. 6 shows in detail the automatic air control and the means for actuating it upon stopping of the braiding machine;

Fig. 7 is a vertical longitudinal section through 30 the steaming device, Fig. 8 is a section of the same on the line 3-8 of Fig. '7, and Fig. 9 is a cross-section on the line 9 9 ofFig. 7.

Fig. 1 showsicertain essential parts of a'comlower plate I! and an upper slotted plate II, the -slots in which determine the travel of the carriers |2' which are driven by the gear train l4. Each carrier holds the usual cylindrical crosswound spool i5 and is provided with the usual 'yarn tensioning device IS. The upper and lower plates l0 and II have corresponding central apertures l8 and i9 through which passes the tubing which is to be covered. (After being covered, the tubing is designated 20'.) The tubing is usually unwound from a reel (not shown) underneath the machine. As is well known, the carriers, ofwhich there are usually 24 or 36, travel about the tubing in such manner as to weave a braid thereon. The tubing passes upto wardly over a rotating capstan 2| which is'driven through the pinion 22 by the gear 24 which is fixed on the cross-shaft 25 The pinion 22 'meshes with a ring gear 26 which is fastened to the side of the capstan 2|. To hold the tubing 55 in contact with the capstan, a spring-actuated roller 28 L is usually provided and is pressed against the capstan by any suitable means. As the tubing 20 passes off of the capstan -2|, it is directed through a steaming device 29.-

For the purpose of maintaining the tubing 20-20 under an inflating pressure during the braiding process, a short length of flexible tubing 30 is provided with a fitting 3| which can be inserted into the end of the tubing 20. The tub- 05 ing 30 is connected tora compressed air line 32 which may be equipped with a pressure gauge 34. The other end of the tubing, 20, may be made air-tight by folding it over and clamping it as shown at 33. V 70 In the usual method of braiding directly on the tubing,..as distinguished from the other known method of braiding on a hollow pin or mandrel from which the formed braid is slipped off onto the tube passing therethrough, the tub 75 0 the normal braiding point of the machine.

guide arm usually found on braiding machines.

aiding machine including a fixed well known in the art.

ing is drawnthrough the machine by the capstan 2|, the carriers 2 rotating around it, and

the yarns or wires 35 are drawn from their spools I5 through'the tension devices l6 at an angle to the tubing which is determined by its rate of travel, the speed of the machine. and the tension. The angle so formed between the tubing and the yarns will be referred to herein as the braiding angle, and the point at which the braid is formed on the tubing as the braiding point. a

In accordance with the present invention, how-- ever; the braid is formed within the orifice of a die 36 which is held by a set screw 38 in an arin 39. The arm 39 is rigidly secured to any convenient part of the frame of the machine (not shown). In order to assure that the braid will not be formed before the tubing passes through the die 36, this die is positioned slightly below The which loosely surrounds the tubing above the braiding point, may be adapted to hold the die 36 and then lowered so as to hold the die below the braiding point.

Referring to Figs. 2, and 3, the die 36 is provided with a cylindrical opening 40 slightly larger in diameter than the inflated covered tubing. At its lower end it is provided with a restricted cylindrical orifice 4|, the lower edge of which is smoothly rounded as shown at 42. The die is preferably provided with a shoulder 44 to prevent its upward movement in the arm 39.

The size of they openings 40 and 4| through the die 36 will, of course, vary with the size of the tubing being covered. The diameter of the orifice 4| is carefully selected so as to be no greater than the minimum outside diameter of the covered tubing in its inflated condition so that it functions to eliminate irregularities which exist in the diameter of the uncovered tubing 20. The position of the die 36 relative to the feed of the yarns 35 and the normal free braiding point .results in the formation of an artificial braiding point within the confines of the orifice 4|. As explained above, the uncovered tubing 20 is somewhat irregular in diameter and therefore has portions which are undersize and portions which are oversize. The undersize portions, which are the portions of minimum diameter, when covered with braid will fit snugly in the orifice 4|, but as will readily be understood, the oversize portions will be drawn down to the same diameter as the undersize portions as they pass through this orifice, at which point the braid is applied under tension. Preferably a rather high tension is used by placing the proper tension springs on the tension devices IS in amanner This removes most of the elasticity from the yarn and enables it, when formed into a .braid, to compress the tubing at those points where it may be oversize. The pull of the yarn, as will be seen in Fig. 2, is not directly on the tubing but is mainly against the edge 42 of the die 36. As the tubing emerges from the orifice 4|, it may'expand slightly at its oversize portions, but in doing so it will putan additional tension on the threads which will be exerted during the subsequentsteaming operation to again reduce these portions to the desired sizewhile the tubing is in a softened condition.

Referring now to Figs. 1 and 4, it is desirable to utilize a pair of auxiliary gripping wheels 5|) and 5| for drawing the tubing through the die The purpose ofusing the wheels 68 and 6|. to

' draw the tubing through the die 86, instead of depending entirely on the pull exerted by the capstan 2!, is to prevent undue stretching of the somewhat elastic tubing between the'die 86 and the capstan 2|. If the capstan alone is used, the tubing will be stretched when oversize sections are going through the die 86 and is liable .to jump, due to its elasticity,.when the oversize section has passed through the die, thus increasing its rate of travel and producing irregularities in the braid. By exerting the pull on the tubing at a point close to the die, this difliculty is eliminated.

As the tubing 28' leaves the capstan 2|, it passes through a chamber 28 in which solvent is applied for bonding thecovering to the tubing. This chamber is shown-in detail in Figs. 7, 8, and 9, and is constructed as follows: The chamber proper is a sheet metal cylinder, the ends of which are closed except for openings in the upper part through which the tubing passes. These openings are preferably in the,form of short tubes-68 and 6 the edges of which are through the chamber from one side to the other and is secured therein by soldering or the like so that the opening of the pipe is directed away fromthe tubing 28', thus preventing the steam,

which is the solvent used in this embodiment,

from blowing directly against the tubing. The pipe 64 is connected at one end to a steam line 66 in which is interposed a manually operated valve 61 having a hand wheel 68. The other end of the pipe 66 is connected to a compressed air line 68 containing a check valve I8 which permits air to enter the chamber 28, but prevents steam or condensate from entering the air line. At the lowermost portion of the chamber 28;:is it is normally positioned as shown in Fig. 1, it opens into a drain pipe II. In order to obtain the correct amount of steam, the valve 6i is opened untilthe steam can be seen .emerging from the tubes 68 or 6| and it is then shut down to the point where there is just enough steam escaping to be visible.

In the operation of a braiding machine the machine stops automatically whenever a yarn breaks or a spool becomes empty. In order to prevent excessivesteaming of the tubing at such times, which would beliable to damage it, means are provided for automatically scavenging the steam from the chamber 28 immediately upon the stoppage of the machine. -As is shown in Figs. and 6, the air line 68 is controlled by a plunger type air valve 88 which is actuated by 'a plunger 8|. This valve is mounted adjacent the standard trip device62 which is pivotally mounted on the upper plate H of the braiding machine adjacent the grooves, in which the carriers I2 travel. As is well known, when a.

' until the machine is started again by moving yam breaks or a spool becomes empty, 9. shoe 86 on the carrier l2 (Fig. 1) drops to the bottom of the carrier and engages the trip lever 82, the path of the'shoe 85 being indicated in dotted lines in Fig. 6. This moves the lever 82 to the right and 'disengages a clutch (not shown) through the medium of an upwardly extendingstud 88. The lever 82 at the same time presses against the plunger 8| and admits airinto the air line 68, the manually'operated air valve 88 being open at this time. The lever 82 remains in this position, holding the air'valve 88 open,

lever 82 to the left. Immediately on the stopping of' the machine. however, the operator closes the steam valve 61 and thereafter" closes the manual air valve 88. When the machine is again started, the steam .valve 61 is opened and adiusted, and, the plunger air valve.88 then being 88 is opened just as it is whenthe machine stops I itself automatically.

The injection of air into chamber 28 through pipe 68 (see Fig. 9) has the effect of condensing the steam, the condensate draining out through pipe 'II'. The air also blows out around the tubing 28' through the tubes 68 and 61.

.The apparatus for effecting the automatic scavenging of chamber 28 is not claimed herein as it is the subject of my co-pending application Serial No. 390,037, filed as a division hereof.

'the braiding machine and a die 'size relative to the tubing is ins rted in the hold- The operation of the apparatus described above as it is used in carrying out the process of the invention will now be explained. A reel of extruded tubing is placed in position to be fed into 6 of the proper er 38. The length of compressed air tubing 88 is fed through the chamber 28, over the capstan 2i and plugged into the end of the tubing. 28 whidh has been drawn up through the die 86 and between the wheels 58 and 5| for a short distance. '.The carriers l2 are supplied with spools of any desired type of yarn which is drawn through the tension devices and fastened around the tubing 28 in known manner. The other end of the tubing 28 is clos'ed'air-tight and the air pressure is'turned on.

The amount of air pressure in the tubing at the time of braiding may be varied within fairly wide limits, the actual pressure used depending upon the size and thickness of the tubing, the gauge and tensile strength used, etc. In actual practice 7) that pressures from 30 to pounds are satisfactory. If the pressure is too high in relation to the size of the tubing and the strength of the yarn, the yarn may not be strong enough to hold the tubing against expansion in its softened state in the chamber 28. If the air pressure is not high enough, the undersize sections thereof may not be held in close contact with the orifice M in die 36 and oversize portions may become creased or buckled in going through the die. Also, the wheels '68 and 6| may not grip the tubing sufliciently to prevent slipping becausethe pres-- sure is too low to enable the wheels to grip the tubing with suflicient friction.

The braiding machine is then started by moving lever 82 to the left and the braiding operation is carried out in the usual manner until the tubing 20' approaches the chamber 29. The steam valve 61 is then opened by the proper amount to fill the chamber 29 with steam so that a slight amount escapes therefrom. The manually operated air valve 90 is then opened. As the tubing 20 is drawn through the die it is reduced to a uniform diameter and; the application of the braid the reto within the orifice M, under tension, maintains the diameter substantially uniform. As the covered tubing 20 passes through the chamber 29, it is subjected to a steam bath which penetrates the fabric cover and softens the plastic tubing, rendering the;

surface thereof adhesive by its solvent action. After the tubing 20' emerges from the chamber 29 and while it is still under an inflating pressure, the excess water evaporates and the surface of the tubing and the braid are dried out, forming a firm adhesive bond between the tubing and its covering.

Whenever the braiding machine is stopped, either manually or automatically, air is immediately blown into-the chamber 29 which prevents the steam from unduly' softening the tubing or excessively wetting the fabric'cover. As soon as,

the machine stops, the operator" turns off the steam and the air, resetting the steam and air valves as described above, and'the machine is again started. Inasmuch as the inflating pressure on the tubing being covered is maintained until the covering operationon the entire length of tubing has been completed, the tubing becomes sufliciently dry while under pressure to maintain its now uniform size when the tubing is disconnected from the air line 30.

By the process and apparatus described above,

. it is possible to produce tubing of greatly improved uniformity which can be held to much closer tolerances and which can be subsequently covered with other materials in known manner and applied to standard size fittings in a much more satisfactory manner than has heretofore been possible.

While the invention has been described with relation to a specific apparatus and as carried out in the covering of a specific type of tubing, this description has been given only by way of example and is not to be taken as limiting the invention to the particular details described.

What is claimed is:

1. The method of covering plastic tubing with a textile fabric formed directly thereon which comprises maintaining said tubing under an inflating pressure, drawing the inflated tubing through a die orifice the diameter of which is no greater than the minimum outside diameter of the inflated covered tubing, said die being so positioned in a machine for forming tubular fabric tioned in a machine for forming tubular fabric that the formation of said fabric takes place within said orifice, weaving the fabric on the tubin as it is drawn through said orifice and treating the covered tubing with solvent for the tubing to bond the covering thereto.

' 3. The method of covering a plastic tubing with braid which comprises maintaining said tubing under an inflating pressure, drawing the inflated tubing through a die orifice so positioned in a braiding machine that the braiding point is within said orifice, the diameter of said orifice being no greater than the minimumoutside diameter of the inflated covered tubing,'and forming the braid on the tubing as it is drawn through said die.

4. The method of covering a plastic tubing with braid which comprises maintaining said tubing under an inflating pressure, drawing the inflated tubing through a die orifice so positioned in a braidingmachine that the braiding point is within said orifice, the diameter of said orifice being no greater than the minimum outside diameter of the inflated covered tubing, forming the braid on the tubing as it is drawn through said die, applying solvent to the tubing through the braid to produce a bond therebetween, and thereafter removing the excess solvent.

5. The method of covering a plastic tubing with braid which comprises maintaining said tubing under an inflating pressure, drawing the inflated tubing through a die orifice so positioned in a braiding machine that the braiding point is within said orifice, the diameter of said orifice being no greater than the minimum outside diameter of the inflated covered tubing, forming'the braid on the tubing as it is drawn through said die, and passing the tubing through vapor of a solvent for the tubing under conditions permitting the solvent to penetrate the braid.

6. The method of covering polyvinyl alcohol 'tubing with braid which comprises maintaining said tubing under an inflating pressure, drawing the inflated tubing through a die orifice so positioned in a braiding machine that the braiding point is within said orifice, the diameter of said orifice being no greater than the minimum outside diameter of the inflated covered tubing, forming the braid on the tubing as it is drawn through said die, and steaming the covered tubing for a sufficient time to permit the steam to penetrate the braid and render the surface of the tubing adhesive.

tubing which is non-uniform its diameter with a textile fabric and simultaneously rendering the diameter of the covered tubing substantially uniform, which comprises drawing said tubing through a die orifice, said orifice being positioned at such a point in a machine for weaving a tubular fabric that said fabric is formed within said orifice, the diameter of said orifice being no greater than the minimum diameter .of the covered tubing whereby the diameterof the tubing is made uniform as it passes through said die, and weaving a cover on said tubing at it passes through said orifice under suflicient tension to maintain said uniform diameter.

- KARL PAPE.

7. The method of coveriraizgp plastic extruded 

